Egg white nutrients composition

The white of the egg contains 365 of water, 13% of protein, and 0.25% of fat and mineral salts. The yolk contains 51% of water, 16.65 protein, 31.7% fat, 1% mineral and vitamins A, D, thiamine and riboflavin and nearly all the cholesterol in the egg. The diet of the hen has no effect on the amino acid composition of the egg.

Egg white proteins differ markedly fro the proteins of the egg yolk in biological function and structure. Egg white is almost a pure solution of protein, almost all proteins of egg white being active as enzymes, inhibitors or antibodies. Their main function is to protect the embryo from microbial factors. The most abundant proteins in the avian egg white are ovalbumin (54%), conalbumin (13%), ovomucoid (11%) and lysozyme (3.5%). Conalbumin is an antibacterial factor which binds metal ions, including iron. Ovomucoid is a glycoprotein which inhibits the proteolytic action of trypsin and lysozyme is an enzyme that causes lysis of microorganisms by breaking down carbohydrates polymer in their cell wall.

Egg white has the ability to form stable foams. Egg white proteins are easily denatured, and the foaming capacity is impaired as a result of heating, freezing and dehydration. Avidin, an egg white protein, is inactivated by heating. It prevents the absorption of biotin. The consumption of large amount of egg can cause biotin deficiency.